Muséum National d'Histoire naturelle, UMR CNRS 7205, 55 rue Buffon, 75231 Paris, France.
Infect Genet Evol. 2013 Jun;16:113-21. doi: 10.1016/j.meegid.2013.01.003. Epub 2013 Jan 26.
A new Oxyurid genus and species are described in a rodent recently discovered in Lao PDR: Laonastes aenigmamus which happens to be the single survivor of the Diatomyidae, a family considered to be extinct since the Miocene. The morphological characters of the new parasite species allow classifying it within the Syphaciinae Railliet, 1916, a subfamily whose members are exclusively parasites of Lagomorpha and Rodents. Male Syphaciinae have developed several types of ventral cuticular ornamentation used to firmly grip the female during mating. The ornamental characters observed in the new species include a finger like appendix, which, until now, has not been described in the subfamily. The originality of this apparatus justifies the creation of a new genus and a new species for the pinworm parasite of Laonastes. Using morphological characters, the new species is analyzed phylogenetically to describe its affinities with representatives of the main groups distinguished within the Syphaciinae. The phylogenetic study produces a cladogram similar to the phylogeny recently proposed for the hosts of the subfamily and in agreement with a close association of the Diatomyidae with the Ctenodactylidae. Such a phenomenon of cophylogeny is interpreted as the result of the existence of a strict specificity between the Syphaciinae and their respective hosts, due to the very close adaptation of their life cycle with the behaviors of their hosts. In Lagomorpha and Rodents, caecotrophy and grooming activities allow a direct transmission of the parasite eggs and favor successive self-infestations, increasing the chances for the parasite to maintain itself in the same host species but decreasing the probability of host switching. The resulting high host specificity allowed the Syphaciinae to out-compete other pinworms and maintain themselves in their specific host over millions of years.
拉昂内斯盲肠球虫，该物种恰好是被认为自中新世以来已经灭绝的双腔科的唯一幸存者。这种新寄生虫的形态特征允许将其归类为旋尾亚科（Syphaciinae Railliet, 1916），该亚科的成员仅寄生在兔形目和啮齿目动物身上。旋尾亚科的雄性寄生虫具有几种类型的腹侧角质装饰，用于在交配时牢固地抓住雌性。在新物种中观察到的装饰特征包括一个手指状的附属物，直到现在，在该亚科中还没有描述过。这种装置的新颖性证明了为拉昂内斯盲肠球虫创造一个新属和一个新种是合理的。利用形态特征，对新物种进行了系统发育分析，以描述其与旋尾亚科主要类群代表的亲缘关系。系统发育研究产生了一个类似于最近为该亚科宿主提出的系统发育树的系统发育树，并与双腔科与栉趾鼠科的密切关联一致。这种共进化现象被解释为旋尾亚科与其各自宿主之间存在严格特异性的结果，因为它们的生命周期与宿主的行为非常密切适应。在兔形目和啮齿目动物中，盲肠营养和梳理活动允许寄生虫卵直接传播，并有利于连续的自我感染，增加了寄生虫在同一宿主物种中维持自身的机会，但降低了宿主转换的可能性。由此产生的高宿主特异性使旋尾亚科能够在数百万年的时间里与其他蛔虫竞争，并在其特定的宿主中维持自身。
